AD9984A SOG Signal

Dear

I 'm test 9984a output signal SOG, found that when the Green channel data (such as pure Green image display), SOG signal can keep normal line of effective time, when the Green channel no data (display pure red picture), SOG signal has been lower, only good will pull up a cycle during blanking, is fetching SOG waveform in the attachment.May I ask if this is the normal SOG output of AD9984A?